In order to enable various products, particularly food products, to be produced and sold at competitive prices, substantial effort has been expended in creating equipment which is capable of automated filling of suitable containers with the desired product and automated closing and sealing of the filled containers. In this regard, one type of container, which has become extremely popular in the food industry, are transparent, plastic containers. One such container is the clamshell container which typically incorporates a base, in which the food product is retained, and an integrally attached lid which is constructed for arcuate pivoting movement relative to the base. In addition, both the base and lid of the container incorporates flanges on which cooperating sealing lugs or interlocking elements are formed, which are lockingly engaged with each other to close and seal the container.
Another principal container is a plastic container which incorporates either a separate base and lid or a hinged lid and base, with each component having a cooperating perimeter seal. By employing sealing flanges which surround the base and lid, the components are secured together by lockingly interengaging the cooperating perimeter sealing components.
In order to assist manufacturers of the particular food product to be able to manufacture and distribute their product efficiently and economically, container filling and closing systems have been developed. In this regard, substantial effort has been expended in improving such equipment, in order to achieve a container closing and/or filling system which effectively satisfies all of the requirements of the food manufacturer. However, in spite of the substantial effort expended, such a system does not exist.
One of the particular problems which has plagued this industry, is the inability of prior art container closing systems to repeatedly and reliably securely engage the locking lugs or locking elements formed on the plastic containers or the entire interlocking perimeter seals along the length of the container. Typically, prior art systems employed to close containers with locking lugs/elements advance the locking lugs/elements of the plastic containers through fastening wheels, which force the locking lugs/elements into engagement with each other. However, it has been found that these prior art systems are incapable of assuring that the locking lugs/elements are maintained in locked engagement after passage through the wheels.
Similar prior art problems exist with the systems employed to close perimeter seal containers. In these systems, belt drive members are employed to contact the top of the container in an attempt to force the lid downwardly into locked engagement with the base. However, these systems have been found to be ineffective in achieving the desired goal. Instead, these prior art systems apply insufficient pressure, leaving the seals open or disengaged in certain areas or, alternatively, excess pressure is applied, causing the container to buckle or deform.
In attempting to solve this problem, heavy gauge material has been employed to resist the compression forces. Unfortunately, this solution is extremely costly, and has not proven to be universally successful.
In most container constructions, employing locking lugs and receiving wells, the locking lugs are typically formed in the flange extending from the front edge of the container, while the receiving wells are formed by the flange extending from the front edge of the base. In attempting to securely engage the locking lugs and receiving wells, the prior art automated, container closing systems advance the flanges through rotating wheels which force the locking lugs/receiving wells into engagement with each other. However, it has been found that in most instances, although the leading locking lug/well is engaged after passage through the rotating wheels, this leading locking lug/well becomes disengaged as the second locking lug/well passes through the rotating wheels for engagement thereof.
As a result, these prior art container closing systems result in the production of partially closed containers, while the prior art perimeter sealing containers are also partially closed or crushed. Although numerous alternate constructions in such systems have been pursued in an attempt to solve these recurring problems, such prior art systems have been incapable of fully satisfying this need.
Furthermore, no single system has been developed which is capable of closing and sealing both types of containers. Consequently, separate equipment or machines are required for each container type.
Therefore, it is a principal object of the present invention to provide a fully automated, universally applicable, product holding container closing system which is capable of completely sealing any desired product holding container without any containers being partially sealed, partially closed, and/or crushed.
Another object of the present invention is to provide a fully automated, universal, product holding container closing system having the characteristic features described above, which is capable of consistently, reliably, efficiently, repeatedly, and dependably producing fully closed containers.
Another object of the present invention is to provide a fully automated, universal product holding container closing system having the characteristic features described above which is fully automated, requiring virtually no manual effort to achieve the desired result.
Another object of the invention is to provide a fully automated, universal product holding container closing system having the characteristic features described above which is capable of completely sealing any container, regardless of the particular configuration employed and regardless of the sealing elements used on the container.
Other and more specific objects will in part be obvious and will in part appear hereinafter.